Mosaics and mosaic making information from The joy of shards
How to make a mosaic planter
The starting point here is a terracotta planter and a collection of broken crockery. The planter will be used indoors and is varnished on the inside. For the porous outside of the pot I've applied some diluted PVA (white craft) glue to reduce the amount of water which the terracotta will draw from the adhesive and grout. I've started to snip up the crockery using tile nippers, but there's more work to be done. The smaller the pieces, the more snug they will fit to the curved surface, but for this design I'd like to keep the shards as large as I can.
Now the shards are at the right sort of size. I've measured the surface area of the planter and laid out the shards to make sure I've got enough. On a plastic sheet I've put a pile of grey cement-based grout powder, which I'm going to use as the adhesive. Always take great care when using cement-based products.
Wearing rubber gloves I put a blob of the grout in the cavity of each curved shard and press it onto the planter. Usually the grout will have enough "grab" to allow you to work steadily round an object like this without the shards falling off. However, if they are slipping you'll have to wait while they set. Be careful, too, that they are secure before you turn the pot to rest on areas you've already mosaicked. When the whole planter is covered, allow the cement to set thoroughly. However, if you can remove any grout which is on the surface of the shards at this stage, life is easier later. It's good to let cement set slowly, so covering the work in a plastic bag will help.
Finally, grout the pot with more of the same cement-based mix.